Calculations of cost-optimal levels of energy performance requirements for renovated buildings and building elements: A latvian case

This research work describes cost-optimal calculations for existing buildings of different categories and main building elements, as well as comparison with the existing energy requirements. Calculations are based on Directive 2010/31/EU and on the Commission Delegated Regulation (EU) No 244/2012 with the associated Guidelines. Those documents are used both – for the calculation of cost-optimal energy performance for a whole building (MWh or kWh/m² per year) and for the assessment of optimal U-value for different building elements. The study starts with the choice of reference buildings according to the statistical data and selection of materials, constructions and systems incl. renewable energy resources, and defining of appropriate packages of energy saving measures. In the next step calculations of final heating and cooling energy, as well evaluation of total primary energy consumption (MWh) are determined have been made. Parallel to that costs of construction works are being estimated according to an actual market situation. The economic calculations are carried out, taking into account expected energy price increase, discount rate and operating costs during the calculation period. As a main result cost-optimal values for both-U-values for different structures after insulation/replacement and for total energy level of overall building renovation are determined. Comparison with existing requirements has been made. In parallel with this, the sensitivity analysis of the future energy prices, operating/maintaining costs and renovation costs is performed. It is shown, that the role of mentioned assumptions may me even decisive in determining of the global costs and cost-optimal levels.